Selective catalytic reduction (SCR) systems have been widely used to meet the emission regulations and two-cell SCR systems have shown the advantages of high NO$_{x}$ conversion efficiency and low NH$_{3}$ slip simultaneously. However, it is noteworthy that the catalyst performance of SCR device would degrade over the service time gradually. If the performance degrading is not well-compensated, the NO$_{x}$ conversion efficiency would reduce significantly. Different from detecting the aging issue in the laboratory, a practical method is to design an observer to estimate the aging factor online such that the urea injection can be modified accordingly. In this paper, we aim to construct an aging-factor observer for two-cell SCR systems. In order to reduce the algorithm computational load and guarantee the implementation performance, we propose a dual time-scale algorithm based on two-cell SCR model and unscented Kalman filter. There is a fast time scale and a slow time scale in the algorithm. Two simulation studies of constant aging factor and time-varying aging factor are investigated in the simulation environment of MATLAB/SIMULINK. The simulation results indicate that the proposed dual time-scale observer works well under different conditions and the calculational load is reduced significantly.

中文翻译：

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通过双时间尺度无味卡尔曼滤波器估计双电池柴油发动机 SCR 系统的水热老化因子

选择性催化还原 (SCR) 系统已广泛用于满足排放法规，双电池 SCR 系统已显示出高 NO$_{x}$ 转换效率和低NH$_{3}$同时滑。然而，值得注意的是，SCR 装置的催化剂性能会随着使用时间的推移而逐渐降低。如果性能下降没有得到很好的补偿，NO$_{x}$转换效率会显着降低。与在实验室中检测老化问题不同，一种实用的方法是设计一个观测器来在线估计老化因子，从而可以相应地修改尿素喷射量。在本文中，我们旨在为双电池 SCR 系统构建一个老化因子观测器。为了减少算法计算量并保证实现性能，我们提出了一种基于双单元SCR模型和无迹卡尔曼滤波器的双时标算法。算法中有一个快的时间尺度和一个慢的时间尺度。在MATLAB/SIMULINK仿真环境中，对恒定老化因子和时变老化因子进行了两项仿真研究。